You may have come across many schematics and projects about a cell phone controlled land rover in many websites. But this is not the same. This article will show you how to make a cell phone controlled land rover without using a microcontroller. You read it right we are not going to use any kind of costly microcontroller for making the rover.
We’ll just need a DTMF decoder MT8870 and a motor driver L293d for making it. So no circuit complexity, no costly ICs and no programming required.
A DTMF decoder is a device which takes a signal from the headset line of a cell phone and gives a 4 bit output corresponding key pressed in the cell phone. Whenever a key is pressed in the mobile, a sum of two fixed frequency is sent as input to the decoder IC. This IC converts the number into its corresponding binary value for example if 3 is pressed its binary value 0011 is produced at the output.
The motor driver L293d can control 2 motors bi-directionally and has 4 inputs. The 4 outputs from the decoder IC is fed into the 4 inputs of the motor driver directly without using complicated circuits.